Response of Ge photon detectors to beta-rays and possible reduction of photopeak areas due to beta–gamma coincidence summing effects

•The possible effects arising from β–γ and X–CE coincidence summing are shown.•A spectrum of CEs was measured without absorbers, positioned close to detector window.•Results suggest that β-absorbers are required in γ-spectrometry to eliminate coincidences with electrons.

In the use of photon detectors having sensitivity to β-rays or internal conversion electrons (CEs), β–γ and/or X–CE coincidence summing may arise. In particular, an n-type germanium detector has a thin dead layer and window, causing considerably higher sensitivity to β-rays and/or CEs especially when sources are located at a small source-to-detector distance. In the present research, reduction of the photopeak area due to β–γ or X–CE coincidence summing has been studied for three germanium detectors.